I have done tests on S9 12.5T and S9 Hydro 18.0T. Bitmain has started signing the latest firmware so nasties cannot get into the miner and change the config' to their own wallet address etc. You can recognise the signed firmware as it has a '.sig' or '.signed' element in the firmware file name near the end. If you flash up to this sig firware you cannot flash over to non sig firmware.

If you are an Antminer S9 Hydro user who was tempted to try non S9 Hydro firmware your miner will report errors in the kernel log. You will also see nothing much in the 'Miner status' and think you have fried or broken your S9 Hydro.

The resolution is to use t9+ -SD Tools.zip and unzip the file. You then get a folder and you copy the files in the folder (not the folder itself!) onto an SD card. You DO NOT need to use a flashing tool such as balenaEtcher or diskimager.exe. It is just a plain copy and paste. Then put the SD card into your miner with it turned off, must be off!

S9 - Put the SD in upside down and change the JP4 jumper block to the 2 pins closest to the front of the controller card (the end with the Ethernet socket).

S9 Hydro - Put the SD card in the right way up (with logo or print upwards) and make a drawing or take a photo of the JP4 jumper block as it is. To make the S9 Hydro boot from the SD just remove the jumper block and put it somewhere safe.

Then for both miner types power up. Wait and wait until both red and green LED's (little lights) flash simultaneously NOT just once but continuously. This is the miner telling you it has used the SD card contents to flash over the chip contents.

Then power down. Put the jumper blocks back as they were originally and remove the SD card. With S9 the jumper block goes onto the JP4 pins furthest from the front. With the S9 Hydro just replace the JP4 jumper block onto the 2 pins that are closest to the edge of the controller card.

Your MAC address and IP will have changed. If it was a static IP it will now be dynamic. Use Bitmains own 'IPreporter' software. Do not forget to click the start button on the software and then press the 'IP report' button on the front of your miner. The IPreporter software will then return the ip address. Use this address in a web browser to access your miner. Don't forget if you make the IP address static, as soon as you do so, the web browser address is invalid; just type the new last octect in. EG: 192.168.1.134 as dynamic will change to what you state it to be when static, say 192.168.1.24.

Also your firmware will now be T9 based but at least I got you in. You can now use a backup or download an older non sig firmware and flash it up. You can always fall back on the SD card if you mess up. I advise you follow what Bitmain advises and use signed firmware. Sometimes it appears at the bottom of the list or sometimes at the top. Also, if you click on 'firmware' on the Bitmain site and see nothing, just scroll up. It's up top.

If you use Awesome miner SSH (elevated privileges) Putty or any SSH tool with a sig firmware it will keep its door closed and you will not be able to connect. With Awesome miner upgrade and you can use your Antminer GUI login name and password. Change them from root and root or root and admin to something else for safety. Also as previously mentioned do flash up to the signed versions even if you rollback to non sig unsigned versions for testing or different miner config' boxes available.

Links to....IPreporter https://shop.bitmain.com/support/download?product=IP-reporter

t9+ -SD Tools.zip https://shop.bitmain.com/support/download?product=Flashing%20SD%20card%20with%20image

It is 3 up from the bottom of the list.

Enjoy!

Please tip me with BTC at 3M3cEWUF81YBRQhL9eX9QdwAWRmfZoqU9W if I have helped you

No it doesn't as at 25th May 2019. I flashed my S9 hydro with normal S9 asicboost, the new one with the .sig. signature image. Now it's bricked because Bitmain will not write a .sig. version for the S9 Hydro AND, the image/firmware that is in there blocks any SSH or none .sig. files.

There is only one firmware for the S9 Hydro anyway here --> https://service.bitmain.com/support/download?product=S9-Hydro (scroll up if you can't see it!)

The S9 Hydro is not just a water-cooled S9. It has a different controller board and uses 24 pin ribbon cables as opposed to 18 pin ones on S9's.

That site containing reviews might be a scam too! Does anyone know if it is truly independent?

I just ordered a S9 12.5TH/s and then they announce the T9. Same chips, uses more power but more stable apparently. So has anyone else bought an S9 12.5 TH/s? I been keen to know how you get on. This is my first one. 

I need to know more......please advise if you dream a lot or there is some substance to your belief.

I'd try and remove all emotion. It has no place in buying/selling and trading (NOT investing, which is a different matter altogether). Read Toni Turners books on scalping, momentum trading and then try the Plus500 website to lever your power. It's highly risky and even of you are buying manually from one website to and selling onto another one (a bit like arbitrage) you will not make day job money regularly and sustained. Bitcoin is listed on Plus500 under 'Virtual' and trades 24/7 more or less.
I would advise doing day job/career and saving and then spending £1500 on a https://shop.bitmain.com/market.htm?name=antminer_s9_asic_bitcoin_miner with power supply and mining Bitcoin or Gridcoin. This mining rig is a solar system first! It is bonkers fast, achieving 16 Tera Hertz per second of crunching. It will mine enough Bitcoin to pay you the £1500 back, in about 1 year. From then on its profit. Check out Ethereum as well.